Closed-loop sensor on a solid-state object position detector

ABSTRACT

The present disclosure discloses an object position detector. The object position detector comprises a touch sensor formed as a closed loop and having a physical constraint formed on an upper surface of the touch sensor and coextensive with the closed loop. The touch sensor is configured to sense motion of an object proximate to the closed loop. The object position detector also comprises a processor coupled to the touch sensor and is programmed to generate an action in response to the motion on the touch sensor.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/338,765, filed Jan. 7, 2003, now U.S. Pat. No. 7,466,307, whichclaims the benefit of U.S. Provisional Application No. 60/372,009, filedApr. 11, 2002.

BACKGROUND

User interfaces on digital information processing devices often havemore information and options than can be easily handled with buttons orother physical controls. In particular, scrolling of documents and data,selection of menu items, and continuous value controls, such as volumecontrols, can be difficult to control with buttons and general purposepointing devices. These buttons and pointing devices are inherentlylimited in how far they can move or how many options can be selected.For example, a computer mouse, though it can move a pointer or cursorindefinitely, has limits to how far it can move without being picked upand repositioned, which limits its usability in these situations.

Solutions to this problem have included:

a. Keys, such as “page up” and “page down” and arrow keys, that arespecifically designated to maneuver through or control data;

b. Provisions for scrollbars in a user interface which can be used toscroll data long distances by using a standard computer pointing devicecontrolling a cursor;

c. Similarly controlled (as in b.) hierarchical menus or choices;

d. Graphical user interface elements such as “slider bars” and “spincontrols” to vary a parameter over an arbitrary range;

e. Scrolling “wheels” on standard pointing devices;

f. Physical knob controls, which, when used to control a user interfaceare often referred to in the art as “jog dials”. Some knobs and dialsoutput quadrature signals to indicate direction of motion;

g. Trackballs that rely on optically or mechanically sensed sphericalcontrols to provide two-dimensional sensing; and

h. A capacitive two-dimensional object position sensor that can be usedfor scrolling by providing a “scrolling region”, where users can slidetheir fingers to generating scrolling actions.

The disadvantages of these prior solutions are as follows:

a. Designated Keys: These typically require designated space on thekeyboard as well as supporting electronics and physical structures. Keysusually limit the control they offer to the user over the informationbeing scrolled or the function being performed to distinct values. Forexample, page up and page down keys enable the user to increment througha document at a constant rate of page by page only.

b. Scroll bars controlled by a pointing device and a cursor: Theseelements require the user to move long distances across a display and/orselect relatively small controls in order to scroll the data.Additionally, these scroll bars take up room on the display that can beused for other purposes.

c. Hierarchical menus controlled by a pointing device or by keycombinations: These have a similar problem to scroll bars, in terms ofthe complexity of the targeting task that faces the user. First, theuser must hit a small target near the edge of a screen, and then theuser must navigate along narrow paths to open up additional layers ofmenu hierarchy. Shortcut keys, which usually consist of keycombinations, are typically non-intuitive and hard to remember.

d. “Sliders” and “spin controls” controlled by a pointing device or bykey combinations: These have targeting problems similar to scroll barsand hierarchical menus (sometimes exacerbated by the targets usuallybeing even smaller than in the cases of scrollbars and menus).

e. Physical Scroll Wheels on mice: The user is unable to scroll very farwith these wheels due to mechanical limitations in how far the user canmove the wheel in a single stroke. These mechanical limitations arebecause of the construction of the wheel itself or because ofinteractions between the wheel and nearby physical features (such as thewheel mounting or the device housing). The limits on thepractical/comfortable length of the basic finger motion also severelyrestrict the ability of the user to scroll significant distances in onestroke. Additionally, these wheels are mechanically complex and take upa lot of space.

f. Physical knobs or “Jog Dial” controls: These have the disadvantagesof being relatively large and mechanically complex. Similar to thescroll wheel, the knob or dial requires some amount of friction to limitaccidental activation, which increases the difficulty of fineadjustments. Additionally, it is difficult to use a physical knob ordial with a great degree of accuracy, and the knob or dial inherentlyhas inertia that may cause overshoot in large motions. The physicalknobs or dials are often mechanically limited in range of rotationimposed by the construction or by the interactions of the knob or dialwith nearby physical features.

g. Trackballs: These are similar to the physical knobs in that they havethe disadvantages of being bulky and mechanically complex. The trackballis difficult to use with a great degree of accuracy, and the trackballinherently has inertia that may cause overshoot in large motions.Additionally, the trackball presents additional complexity in that itpresents control of two dimensions of motion in a way that makes itdifficult for users to limit their inputs to a single dimension.Finally, the input is limited either by the construction of thetrackball and its housing, or by natural limits on comfortable/practicalfinger motion, or both.

h. Scroll Regions: These are limited by the physical limitation that auser's finger will eventually reach the end of the scrolling region andthe user will have to lift their finger, replace it on the sensor insidethe region, and continue the motion. The user must perform manyrepetitive motions of the same finger to scroll long distances with ascroll region.

The disadvantages of the prior art can be remedied by devising a userinterface that enables scrolling, selecting, and varying controls over along range of possible positions and values.

SUMMARY

The drawbacks and disadvantages of the prior art are overcome by aclosed-loop sensor on a solid-state object position detector.

The present disclosure discloses a solid-state object position detector.The solid-state object position detector comprises a touch sensor formedas a closed loop having a physical constraint formed on an upper surfaceof the touch sensor and coextensive with the closed loop. The touchsensor is configured to sense motion of an object proximate to theclosed loop. The object position detector also comprises a processorcoupled to the touch sensor and is programmed to generate an action inresponse to the motion on the touch sensor.

The present disclosure also discloses a solid-state object positiondetector, comprising a two-dimensional touch sensor having a tactileguide formed on an upper surface of, and coextensive with, thetwo-dimensional touch sensor. The two-dimensional touch sensor isconfigured to sense motion of an object proximate to the two-dimensionaltouch sensor. The solid-state object position detector also comprises aprocessor coupled to the two-dimensional touch sensor and configured toreport only one variable indicating the position, such as the angularposition, of an object proximate to the two-dimensional touch sensor.The processor is programmed to generate an action in response to themotion on the two-dimensional touch sensor.

The present disclosure also discloses a combination comprising asolid-state object position detector, a pointing input device, and aprocessor. The solid-state object position detector has a touch sensorformed as a closed loop. The solid-state object position detector has atactile guide formed on an upper surface of the touch sensor andcoextensive with the closed loop. The touch sensor is configured tosense a first position of an object proximate to the closed loop. Thepointing input device is disposed proximate to the solid-state objectposition detector and is configured to sense a first pointing input of auser. The processor is coupled to the solid-state object positiondetector and to the pointing input device. The processor is programmedto generate at least one action in response to the first position and atleast one action in response to the first pointing input. The pointinginput device can be a mouse, a touch pad, a pointing stick, a slider, ajoystick, a touch screen, a trackball or another solid-state objectposition detector.

The present disclosure also discloses another embodiment of acombination comprising a solid-state object position detector, a controlinput device, and a processor. The solid-state object position detectorhas a touch sensor formed as a closed loop. The solid-state objectposition detector has a tactile guide formed on an upper surface of thetouch sensor and coextensive with the closed loop. The touch sensor isconfigured to sense a first position of an object proximate to theclosed loop. The control-input device is disposed proximate to thesolid-state object position detector and is configured to sense a firstcontrol input of a user. The processor is coupled to the solid-stateobject position detector and to the control input device. The processoris programmed to generate at least one action in response to the firstposition and at least one action in response to the first control input.The control input device can be a button, a key, a touch sensitive zone,a scrolling region, a scroll wheel, a jog dial, a slider, a touchscreen, or another solid-state object position detector.

The present disclosure also discloses a solid-state object positiondetector, comprising a touch sensor having a first electrode and aplurality of second electrodes disposed in a one-dimensional closed loopand proximate to the first electrode. The solid-state object positiondetector also comprises a processor coupled to the touch sensor. Theprocessor generates an action in response to user input on the touchsensor. The complexity of the sensing circuitry used in the plurality ofsecond electrodes can be reduced, such that when only relativepositioning is necessary, at least two of the plurality of secondelectrodes are electrically connected or wired together.

The present disclosure also discloses a combination comprising asolid-state object position detector, a touch pad, and a processor. Thesolid-state object position detector comprises a touch sensor having afirst electrode and a plurality of second electrodes disposed in aone-dimensional closed loop and proximate to the first electrode. Thetouch pad has a plurality of X electrodes and a plurality of Yelectrodes. The first electrode is electrically coupled to at least oneof the plurality of X electrodes and the plurality of Y electrodes. Theprocessor is coupled to the touch sensor and to the input device. Theprocessor generates an action in response to user input on at least oneof the touch sensor and the touch pad. The complexity of the sensingcircuitry used in the plurality of second electrodes can be reduced,such that when only relative positioning is necessary, at least two ofthe plurality of second electrodes are electrically connected or wiredtogether.

The present disclosure also discloses a solid-state object positiondetector, comprising a touch sensor having a plurality of interleavingelectrodes disposed proximate to a one-dimensional closed loop; whereineach electrode is interdigitated with an adjacent neighboring electrode.The solid-state object position detector also comprises a processorcoupled to the touch sensor. The processor generates an action inresponse to user input on the touch sensor.

The present disclosure also discloses a solid-state object positiondetector, comprising a touch sensor having a plurality ofself-interpolating electrodes disposed proximate to a closed loop. Thesolid-state object position detector also comprises a processor coupledto the touch sensor. The processor generates an action in response touser input on the touch sensor.

The present disclosure also discloses a method of calculating a positionof an object on an object position detector comprising receivingpositional data from the object on a touch sensor having a closed loopand interpolating the positional data to determine a position of theobject on the one-dimensional closed loop. The interpolating aspect ofthe method further includes performing a quadratic fitting algorithm, acentroid interpolation algorithm, a trigonometric weighting algorithm,or a quasi-trigonometric weighting algorithm.

The present disclosure also discloses a method of determining motion ofan object on a touch sensor of an object position detector. The methodcomprises receiving data of a first position of the object on a closedloop on a touch sensor of the object position detector, receiving dataof a second position of the object on the closed loop, and calculatingmotion from the second position and the first position. The method canfurther comprise determining if the motion is equal to or greater than amaximum angle and adjusting the motion based on whether the motion isequal or greater than the maximum angle. The method of adjusting themotion can be subtracting 360° from the motion. The method can furthercomprise determining if the motion is less than a minimum angle andadjusting the motion based on whether the motion is less than theminimum angle. The method of adjusting the motion can be adding 360° tothe motion.

BRIEF DESCRIPTION OF FIGURES

Referring now to the figures, wherein like elements are numbered alike:

FIG. 1 illustrates a block diagram of a solid-state closed-loop sensor;

FIG. 2 illustrates a location of a closed-loop sensor on a laptop near akeyboard;

FIG. 3 illustrates a closed-loop sensor disposed on a conventionalpointing device;

FIG. 4 illustrates wedge-shaped electrodes of a closed-loop sensor;

FIG. 5 illustrates lightning-bolt-shaped electrodes of a closed-loopsensor;

FIG. 6 illustrates triangle-shaped electrodes of a closed-loop sensor;

FIG. 7 illustrates rectangular-shaped electrodes that may be used in alinear section of a closed-loop sensor;

FIG. 8 illustrates rectangular-shaped electrodes that may be used in arectangular-shaped closed-loop sensor;

FIG. 9 illustrates another example of triangle-shaped electrodes of aclosed-loop sensor;

FIG. 10 illustrates spiral-shaped electrodes of a closed-loop sensor;

FIGS. 11 to 17 illustrate various shapes of the path utilized on aclosed-loop sensor;

FIG. 18 illustrates a cross-sectional view of V-shaped depressed groovesthat define the path on a closed-loop sensor;

FIG. 19 illustrates a cross-sectional view of a raised projection thatdefines the path on a closed-loop sensor;

FIG. 20 illustrates a cross-sectional view of U-shaped depressed groovesthat define the path on a closed-loop sensor;

FIG. 21 illustrates a cross-sectional view of a bezel that defines thepath on a closed-loop sensor;

FIGS. 22 and 23 illustrate the motions of an input object on aclosed-loop sensor and the effects on a host device;

FIG. 24 illustrates a motion on a closed-loop sensor for navigatingmenus;

FIG. 25 illustrates a motion on a closed-loop sensor for verticallynavigating menus using an additional key;

FIG. 26 illustrates a motion on a closed-loop sensor for horizontallynavigating within open menus;

FIG. 27 illustrates a motion on a closed-loop sensor for a value settingcontrol;

FIG. 28 illustrates a closed-loop sensor electrically connected to atouch pad;

FIG. 29 illustrates the potential electrical connections of twoclosed-loop sensors to a touch pad;

FIG. 30 illustrates several closed-loop sensors electrically connectedto a touch pad;

FIG. 31 illustrates two closed-loop sensors with indicator electrodeselectrically connected to a touch pad;

FIG. 32 illustrates a graph of the signals from a closed-loop sensorwith an indicator electrode electrically connected to a touch pad;

FIG. 33 illustrates a top view of an exemplary closed-loop sensor;

FIG. 34 illustrates a side view of the cross-section of the exemplaryclosed-loop sensor of FIG. 33;

FIG. 35 illustrates the lightning-bolt-shaped electrodes of an exemplaryclosed-loop sensor having an interior opening and four exterior regions;

FIG. 36 illustrates a plurality of closed-loop sensors to vary thesettings of audio controls;

FIG. 37 illustrates two sets of two closed-loop sensors formedconcentrically about a single origin for an audio system;

FIG. 38 illustrates four closed-loop sensors for an audio system formedin concentric circles about a single origin;

FIG. 39 is a flow chart of a method of calculating a position of anobject on a closed-loop sensor by performing a quadratic fittingalgorithm;

FIG. 40 is a graph of the second quadratic fitting step in which thethree capacitance measurements from the three adjacent electrodes arefitted to an inverted parabola;

FIG. 41 is a flow chart of a method of calculating a position of anobject on a closed-loop sensor by performing a centroid interpolationalgorithm;

FIG. 42 is a flow chart of a method of calculating a position of anobject on a closed-loop sensor by performing a trigonometric weightingalgorithm;

FIG. 43 is a flow chart of a method of calculating a position of anobject on a closed-loop sensor by performing a quasi-trigonometricweighting algorithm;

FIG. 44 is a flow chart of a method of determining relative motion of anobject on a closed-loop sensor; and

FIG. 45 is a flow chart of a method of using the angular component todetermine the sign of the traversal along the closed-loop path.

DETAILED DESCRIPTION

Those of ordinary skill in the art will realize that the followingdescription of the present invention is illustrative only and not in anyway limiting. Other embodiments of the present invention will readilysuggest themselves to such skilled persons.

An object position detector is disclosed comprising a touch (orproximity) sensor (or touch pad or touch screen or tablet), such as acapacitive, resistive, or inductive sensor designed to sense motionsalong a substantially closed loop, and referred to herein as aclosed-loop-sensor. This closed-loop sensor can be used to enhance theuser interface of an information-processing device. A loop area on aclosed-loop sensor can be defined by a tactile guide. Preferably, theclosed-loop sensor is defined by a physical constraint. The position ofan input object (or finger or pointer or pen or stylus or implement) ismeasured along this loop. When the input object moves along this loop, asignal (or instruction) is generated that causes an action at the hostdevice. For example, when the input object moves in the clockwisedirection along this loop, a signal is generated that can cause thedata, menu option, three dimensional model, or value of a setting totraverse in a particular direction; and when the input object moves inthe counter-clockwise direction, a signal is generated that can causetraversal in an opposite direction. This looping motion of the inputobject within the loop area need only be partially along the loop, or ifthe looping motion completes one or more loops, be approximate andnotional. A strict loop can imply that the input object would eventuallyreturn to exactly the same position on the sensor at some point.However, the sensor may report the input object's position with greateraccuracy than the input object can actually repeatably indicate aposition. Hence, enabling the sensor to accept a close approximation toa loop as a completed loop is desirable.

A closed-loop sensor can be physically designed or electrically laid outin such a way as to naturally report in only one coordinate. This singlecoordinate design, which will be referred to as “one-dimensional” withinthis document, is one-dimensional in that the closed-loop sensorinherently outputs information only in one variable; the closed-loopsensor itself may physically span two or more dimensions. For example, aclosed-loop sensor can consist of a loop of capacitive electrodesarranged along the perimeter of a closed loop of any shape hereindescribed. The absolute position of the input object on aone-dimensional closed-loop sensor can be reported in a singlecoordinate, such as an angular (θ) coordinate, and the relativepositions (or motions) of the input object can be reported in the same(such as angular) units as well.

The operation of the present invention with a host device is illustratedin the block diagram of FIG. 1. A signal is generated at the closed-loopsensor 10 and is then decoded by the closed-loop path decoder 12. Amessage is generated by the message generator 14 and the message istransmitted to the host device 16. The host device 16 then interpretsthe message and causes the appropriate action on a display (not shown).

Host device 16 is a processing system. The following is a description ofan exemplary processing system. However, the exact configuration anddevices connected to the processing system may vary.

The processing system has a Central Processing Unit (CPU). The CPU is aprocessor, microprocessor, or any combination of processors and/ormicroprocessors that execute instructions stored in memory to perform anapplication or process. The CPU is connected to a memory bus and anInput/Output (I/O) bus.

A non-volatile memory such as Read Only Memory (ROM) is connected to CPUvia the memory bus. The ROM stores instructions for initialization andother systems commands of the processing system. One skilled in the artwill recognize that any memory that cannot be written to by the CPU maybe used for the functions of the ROM.

A volatile memory such as a Random Access Memory (RAM) is also connectedto the CPU via the memory bus. The RAM stores instructions for processesbeing executed and data operated upon by the executed processes. Oneskilled in the art will recognize that other types of memories, such asflash, DRAM and SRAM, may also be used as a volatile memory and thatmemory caches and other memory devices may also be connected to thememory bus.

Peripheral devices including, but not limited to, a storage device, adisplay, an I/O device, and a network connection device are connected tothe CPU via an I/O bus. The I/O bus carries data between the devices andthe CPU. The storage device stores data and instructions for processesunto a media. Some examples of a storage device include read/writecompact discs (CDs), and magnetic disk drives. The display is a monitoror other visual display and associated drivers that convert data to adisplay. An I/O device is a keyboard, a pointing device or other devicethat may be used by a user to input data. A network device is a modem,Ethernet “card”, or other device that connects the processing system toa network. One skilled in the art will recognize that exactconfiguration and devices included in or connected to a processingsystem may vary depending upon the operations that the processing systemperforms.

The closed-loop sensor (or several closed-loop sensors) can be disposedin any location that is convenient for its use with a host device, andoptional other input devices. A host system can be a computer, a laptopor handheld computer, a keyboard, a pointing device, an input device, agame device, an audio or video system, a thermostat, a knob or dial, atelephone, a cellular telephone, or any other similar device. Forexample, the closed-loop sensor can be positioned on a laptop near thekeyboard as illustrated in FIG. 2. The base 20 of the laptop isillustrated having a keyboard 22, a touch pad (or touch screen) 24, anda closed-loop sensor 26. Alternative positions include positioning theclosed-loop sensor on or connecting it to a conventional computer orkeyboard. FIG. 3 illustrates the closed-loop sensor 26 disposed on aconventional pointing device 28. Conventional pointing device 28 mayhave other features, such as left click or right click buttons, whichare not shown.

The closed-loop sensor of the present invention can also be implementedas a stand-alone device, or as a separate device to be used with anotherpointing input device such as a touch pad or a pointing stick. Theclosed-loop sensor of the present invention can either use its ownresources, such as a processor and sensors, or share its resources withanother device. The closed-loop sensor can be a capacitive, resistive,or inductive touch or proximity (pen or stylus) sensor. A capacitivesensor is preferred, and is illustrated herein.

The closed-loop sensor can be implemented as a stand-alone sensor, whichcan then be used as a replacement for one or more knobs, sliders, orswitches on any piece of electronic equipment. In some cases, it mightbe desirable to provide visual feedback indicating the “current” settingof the virtual knob, such as a ring of light emitting diodes (LEDs)surrounding the closed-loop region. An Etch-a-Sketch™ type of electronictoy can be implemented using a single position detector with twoclosed-loop sensors or two position detectors with one closed-loopsensor each. Many other toys and consumer appliances currently haveknobs used in similar ways that can benefit from the present invention.

The closed-loop sensor can have electrodes (or sensor pads) that are ofvarious shapes and designs (e.g., a simple wedge or pie-shape, alightning-bolt or zigzag design, triangles, outward spirals, or thelike) configured in a closed-loop path. A closed-loop sensor 30 havingwedge-shaped electrodes is illustrated in FIG. 4, while a closed-loopsensor 34 having lightning-bolt-shaped electrodes is illustrated in FIG.5. The sensor pattern can be designed so that it can have continuousinterpolation between the electrodes. The sensor pattern can also bedesigned so that the electrodes interleave between each other to helpspread the user's input signal over several electrodes.

FIG. 4 illustrates the wedge- (or pie-)shaped electrodes in aclosed-loop capacitive sensor 30. When an input object (or finger orpointer or stylus or pen or implement) is over first electrode 31, onlythe first electrode 31 senses the largest change in capacitance. As theinput object moves clockwise toward electrodes 32 and 33, the signalregistered by first electrode 31 gradually decreases as the signalregistered by the second electrode 32 increases; as the input objectcontinues to move further clockwise toward third electrode 33, the firstelectrode 31 signal drops off and the third electrode 33 starts pickingup the input object, and so on. By processing the electrode signals inlargely the same way as for a standard linear sensor, and taking intoaccount that there is no true beginning or end to the closed-loopsensor, the object position detector having the wedge sensor caninterpolate the input object's position accurately.

FIG. 5 illustrates the lightning-bolt-shaped electrodes in a closed-loopsensor 34. The lightning-bolt design helps spread out the signalassociated with an input object across many electrodes by interleavingadjacent electrodes. The signals on a closed-loop sensor withlightning-bolt shaped electrodes are spread out in such a way that theelectrode closest to the actual position of the input object has thelargest-signal, the nearby electrodes have the next largest signal, andthe farther electrodes have small or negligible signals. However,comparing a lighting-bolt sensor with a wedge sensor with a similar sizeand number of electrodes, an input object on the lightning-bolt sensorwill typically couple to more electrodes than in the wedge sensor. Thismeans that the lighting-bolt sensor will have more information about theinput object's position than a wedge sensor, and this effect helpsincrease sensor resolution and accuracy in sensing the input object'sposition. For best results, the electrodes of the lightning bolt sensorneed to be sufficiently jagged in shape such that the input object onthe sensor will always cover more than one electrode. The interleavingnature of this electrode design means that the spacing from oneelectrode to the next can be larger than in the wedge sensor while stillproviding similar resolution and accuracy. The spacing from oneelectrode to the next with such an interdigitated electrode design mayeven be considerably larger than the expected input object.

Another example is a closed-loop sensor 35 having triangle-shapedelectrodes, as illustrated in FIG. 6. In this case, the odd-numberedtriangle-shaped electrodes (e.g. 37, 39) are wider toward the outer edgeof the closed-loop area and narrower toward the inner edge of theclosed-loop area, while the even-numbered triangle-shaped electrodes(e.g. 36, 38) have the opposite positioning. To compute the inputobject's angular position around the closed-loop sensor, the sameinterpolation algorithm used for other closed-loop sensors can be used.As long as the input object is wide enough to cover at least twoeven-numbered electrodes (e.g., 36, 38) and at least two odd-numberedelectrodes (e.g., 37, 39), interpolation to calculate position along theloop will mostly compensate for the difference in the shapes of the evenelectrodes versus odd electrodes. To compute the input objects radialposition, or position between the inner and outer edges of theclosed-loop sensor area, the total capacitance C_(EVEN) on theeven-numbered electrodes and similarly the total capacitance C_(ODD) ofthe odd-numbered electrodes should be calculated. The radial position isgiven by C_(ODD)/(C_(EVEN)+C_(ODD)). If only radial information isdesired of the closed-loop sensor, then only two distinct electrode setsare needed—all of the odd-numbered electrodes can be electricallyconnected or wired together, and all of the even-numbered electrodes canbe electrically connected or wired together. The triangle design is alsoself-interpolating in the radial position in that the odd-numberelectrodes (e.g., 37, 39) will naturally increase in signal and theeven-number electrodes (e.g. 36, 38) will naturally decrease in signal,when the input object moves from the inner edge of the closed-loopsensor towards the outer edge of the closed-loop sensor; these naturaleffects facilitate determination of the radial position.

As shown in FIG. 6, the odd-number electrodes (e.g., 37, 39) are largerin area than the even-number electrodes (e.g., 36, 38). This means thatthe odd-number electrodes (e.g., 37, 39) may produce a larger signalthan the even-number electrodes (e.g., 36, 38) in response to the sametype of input and cause the simple C_(ODD)/(C_(EVEN)+C_(ODD))calculation of radial position to favor the outer edge. There are manyways to prevent the closed-loop sensor 35 from biasing toward the outeredge when calculating radial position. For example, the signals fromeither the odd-number electrodes (e.g., 37, 39), or the even-numberelectrodes (e.g., 36, 38), or both, can be scaled based on size prior tocalculating radial position, or the radial position produced can beadjusted based on electrode sizes. This unbalanced signal effect is dueto having to accommodate the circular shape of closed-loop sensor 35;for example, a linear sensor with triangular electrodes can easily haveequally sized triangular electrodes.

Rectangle-shaped electrodes 40, 41 can also be utilized, as illustratedin FIGS. 7 and 8, respectively. Another example is a closed-loop sensor42 having triangle-shaped electrodes that are rounded, similar to petalsof a flower, as illustrated in FIG. 9. The design shown in FIG. 9 is amethod of reducing the unbalanced signal effect described above byadjusting the triangle electrodes such that all of the electrodes aresimilar in size. Another example of electrode shapes is shown by aclosed-loop sensor 43 having spiral-shaped electrodes, as illustrated inFIG. 10.

The closed-loop sensor generally utilizes sensor electrodes arrangedalong the shape of a closed, or substantially closed, path (or loop).Several shapes may be used, although a circular path is preferred. FIGS.11 to 17 illustrate various shapes contemplated. The shapes contemplatedinclude a circle, an oval, a triangle, a square, a rectangle, anellipse, a convex or concave polygon, a figure eight, a spiral, acomplex maze-like path, and the like. Other more complex paths arepossible and might be more desirable or more appropriate in somesituations. In addition, the loop sensor can also be nonplanar; forexample, it may be arranged on the surface of a cylinder, a cone, asphere, or other 3-D surface. Also, the loop path may be defined forinput objects of various sizes, perhaps as small as a pen tip and aslarge as a hand.

It is desirable to communicate a definition of the loop path to theuser. There are several means possible to define the path of theclosed-loop sensor including tactile guides and physical constraints. Asillustrated in FIGS. 18 and 20, a physical constraint in the form of adepressed groove can be used to define the path on the closed-loopsensor. The depressed groove can be U-shaped 46, V-shaped 44, or someother cross-sectional shape. FIG. 19 illustrates the use of a physicalconstraint in the form of a raised ridge 45, while FIG. 21 illustratesthe use of a physical constraint in the form of a bezel 48 to define thepath on the closed-loop sensor. Other tactile options are alsocontemplated, including a depressed region, a cutout, a textured region,a tactile label (such as a label with embossing, stamping, or raisedprinting), a rounded protrusion, and the like. The path can also beindicated in a non-tactile manner, such as by LCD projections,non-tactile graphics printed on a label covering the sensor or on thesensor housing, or a display associated with a transparent closed-loopsensor. A tactile guide is preferred when practiced.

There are distinct advantages of having a tactile guide that help retainthe input object along the closed-loop path. Without such a guide, theinput object tends to stray as the user cannot track the loop perfectly,and especially as the user shifts attention between keeping the inputobject within the loop and monitoring the resulting actions in responseto input along the loop. Even with methods to try to compensate for thedeviation from the defined loop (as discussed further herein), theresulting interface is not as user friendly or as amenable to usercontrol as a guide that help retain the input object. There are distinctadvantages to marking the loop path appropriately for the expected inputobject. For example, if a finger is utilized, a groove designed toretain and guide the finger can be used. If a stylus is utilized, asmaller groove can be used to retain the stylus. If a hand is utilized,a larger groove can be used.

Multiple closed paths can be defined on a single input device, each ofwhich controls different features of the user interface. In this case,it is especially desirable to make the location of each loop pathreadily apparent to the user by use of one of the above-mentioned means,such as a bezel with multiple openings.

There are many ways of decoding the user's position along the path. Thehardware of the sensor may be designed, for example, with the loop pathphysically laid out in such a way that the only coordinate reported tothe host computer is already in the desired form.

Alternately, for some loop paths, X/Y coordinates on a traditionaltwo-dimensional sensor can be converted into polar coordinates (with theorigin preferably located in the center of the loop) and the anglecomponent used as the user's position. Multiple closed loops can bedefined on a single two-dimensional position detector and resolved bycalculating multiple sets of polar coordinates with different originsand choosing the closed loop yielding the smallest radial coordinate.More complicated path-based decoding can also be performed by dividingthe path into geometrically simpler regions, and using various methodsdesigned to determine which region contains an input.

Once the user's position on the loop path is determined usingabove-referenced methods, this information can be used in many ways.Successive user locations can be subtracted to decode motion directionor magnitude. This motion can, for example, be converted into scrollingsignals or keystrokes that the user interface can interpret.

In a preferred embodiment, this user motion is only interpreted in arelative manner. That is, the absolute position of the input object inthe loop path is insignificant. This can be advantageous because itfrees the user from having to target an exact starting position alongthe loop. However, it may occasionally be useful to use this absoluteposition (i.e., an exact starting point), for example, to indicate astarting value for a controlled parameter or to indicate the desiredparameter to be varied.

One of the user interface problems that can benefit from the presentinvention is scrolling. To solve the scrolling problem, the motion ofthe user's position on the closed-loop sensor is converted to signals(or instructions) that would cause the user interface to scroll thecurrently viewed data in the corresponding direction. FIGS. 22 and 23illustrate the motions (illustrated by arrow 50) of an input object on aclosed-loop sensor of an object position detector 52 and the effect on ahost device. For the purposes of this disclosure, numeral 52 representsan object position detector. As disclosed herein, the object positiondetector could be any shape.

As the input object moves on the closed loop sensor of the objectposition detector 52, a document on a computer screen 54, for example,is scrolled either up or down depending upon the direction of themovement of the input object. For example, in the case of FIG. 22, thecounterclockwise motion shown by arrow 50 can cause the document 54 tobe scrolled up as indicated by arrow 56, while FIG. 23 illustrates thescrolling of the document down as indicated by arrow 58 with a clockwisemotion (shown by arrow 50) on the closed-loop sensor of the objectposition detector 52.

Navigating through menus is also easier with the present invention. Asillustrated in FIG. 24, a motion either clockwise or counterclockwise(illustrated by arrow 60), on the closed-loop sensor of the objectposition detector 62 would cause the drop down of menu items 64 on, forexample, a computer screen 66. For the purposes of this disclosure,numeral 62 represents an object position detector. As disclosed herein,the object position detector could be any shape. The simplest instanceof this is to convert the relative position signal (or instruction) insuch a way that the menu is navigated depth-first by sending keystrokesor other messages understood by the graphical user interface (GUI) toindicate intent to navigate a menu. One alternative solution for complexmenus is to traverse only the current menu hierarchy level by using theloop method of the closed-loop sensor, and a separate mechanism toswitch between levels in the menu. There are many applicable mechanisms,including physical switches that the user presses, regions on the sensorwhere the user can tap or draw a suggestive gesture, and the like.

It is possible to overload the user interface element controlled by theclosed-loop sensor using physical or virtual “shift” keys or switches,which is similar to the way that the shift key on a keyboard overloadsthe meaning of the keys. For example, the system can be configured sothat unmodified traversal along the path would control scrolling of thecurrent application, but modified traversal by holding down a keyboard's“shift” key can control the volume setting of the audio output. This canbe accomplished with a single sensor by way of mode switching, or bymultiple sensors or regions of a single sensor, as will be illustratedfurther herein.

This mode switching means, such as a “shift key” or other appropriatekey, can cause input on the closed-loop sensor of the object positiondetector 62 to traverse the menu hierarchy orthogonal to the currentlevel. FIG. 25 illustrates the activation of a “shift” key 68 combinedwith a motion (illustrated by arrow 60) on the closed-loop sensor of theobject position detector 62 to move through the menu items 64 on, forexample, a computer screen 66. FIG. 25 illustrates the vertical movement(illustrated by arrow 74) through menus with the shift key 68 activated,while FIG. 26 illustrates the horizontal movement (illustrated by arrow76) through horizontal menu items 72 with the shift key unactivated. Itis also possible to reverse the function of shift key 68, such that notdepressing shift key 68 results in vertical motion through the menuitems 64, while depressing shift key 68 results in horizontal movementbetween menu layers.

The closed-loop sensor of the object position detector 62 also addressesthe “deep menu” problem by enabling the menu to be presented in flatterform on the computer screen 66. Studies have shown that humans arecapable of using, and may even prefer to use, menus in which thesubmenus are displayed in indented form (not shown). However, users havetraditionally had trouble with such menus since maneuvering down such alist may require fine steering control of the cursor or multiplescrolling motions. The present invention, which allows infinitescrolling along a menu, enables the deeper menu to be presented as alonger list, and the depth of the menu reduced.

A value setting control, such as a “spin control” or slider, can bevaried according to the user's input on a closed-loop sensor in asimilar manner by sending keystrokes or other messages understood by theuser interface as indicating an attempt by the user to increment ordecrement the value of the control. FIG. 27 illustrates an example of avalue setting control that controls the volume settings. As illustratedin FIG. 27, a motion, either clockwise or counterclockwise, (illustratedby arrow 80) on the closed-loop sensor of the object position detector82 would cause the setting of the volume control 84 to either increaseor decrease (as indicated by arrow 86) on, for example, a computerscreen 66. For the purposes of this disclosure, numeral 82 represents anobject position detector. As disclosed herein, the object positiondetector could be any shape.

For two-dimensional and three-dimensional graphical presentations, suchas computer aided drafting (CAD), solid modeling, or data visualization,the relative motion of the user's input on the closed-loop sensor can beconverted by the software directly into translation, rotation, and/orscaling of the model or viewport.

Many user interface elements can benefit from the closed-loop sensor.Most can be categorized as being similar to controls for scrolling,menus, or value setting controls. For example, selection among icons ona “desktop” can be performed using this method, with a means (such as agesture on the sensor, a tap on the sensor, a button, or a key) providedfor launching the corresponding program once the user is satisfied withthe selection. This task can be considered analogous to navigating amenu.

Navigation along the “tab order” of the elements of a graphical userinterface can be performed with a closed-loop sensor. Similarly,navigation between multiple running applications, multiple documentsedited by the current application, or multiple modes of a particularapplication can be accomplished with this control.

As an alternative to a separate sensor with a defined path, a specialmode can be implemented on an existing touch pad-style pointing deviceto perform the same function as the closed-loop sensor of the presentdisclosure. For example, a touch pad of a notebook computer is primarilyused for moving a pointer and selecting elements in the user interface.A button, switch, or mode changing tap region on the touch pad can bedefined to change the mode of the touch pad so that it operates as aloop-scrolling device. The user would activate this mode-switchingcontrol, and then move in an approximately closed loop path, preferablycircular, on the touch pad. While this mode is selected, this motion isinterpreted as a scrolling action rather than as the typical pointingaction.

Another mode switching method is possible if the closed-loop sensor candistinguish the number of input objects present. Moving in a circle withtwo input objects (both input objects moving in the same direction, asopposed to when the input objects move in opposite directions or whenone of the input objects does not move significantly) on the closed-loopsensor, for example, can scroll through a set of data, while moving asingle input object can be interpreted as a pointing action. Due to theflexible nature of the closed-loop sensor, other usage modalities arepossible in combination with this fundamental mode of operation.

As stated above, the closed-loop sensor can also share the resources ofa separate touch pad or touch sensor. FIG. 28 illustrates the electricalleads 94 connecting the closed-loop sensor electrodes 91 of aclosed-loop sensor 90 with Y axis electrodes 93 (eight are illustrated)of a touch pad 92. For the purposes of this disclosure, numeral 90represents an exemplary closed-loop sensor and numeral 92 represents anexemplary touch pad. One skilled in the art would recognize that thetouch pad 92 could be any shape, design or configuration. The X axiselectrodes of touch pad 92 are not shown. The leads 94 transmit signalsfrom the Y axis electrodes 93 or the closed-loop sensor electrodes 91,or both, to the Y axis sensor inputs (not shown) of the processor (notshown). Additional leads (not shown) connect the X axis electrodes (notshown) to the X axis sensor inputs (not shown). When an input objecttouches the touch pad 92, the input results in changes in the signals ofboth the Y sensor inputs and the X sensor inputs. In contrast, when aninput object touches the closed-loop sensor 90, the input is read by theelectrodes as changes in the Y sensor inputs only. By checking if the Xaxis signals have changed, the host system can distinguish between userinput on the touch pad 92 and the closed loop sensor 90. If desired, theX sensor inputs can be connected to the closed-loop sensor instead ofthe Y sensor inputs. Alternatively, additional closed-loop sensors canalso be disposed and electrically connected to the X sensor inputs ofthe touch pad.

As illustrated in FIG. 29, one axis of electrodes 95 of a touch pad 92can support more than one closed-loop sensor. Arrow 96 indicates thepotential positioning of leads to a first closed-loop sensor that hassix distinct electrodes, while arrow 98 indicates the potentialpositioning of leads to a second closed-loop sensor.

FIG. 30 illustrates the ability to have several closed-loop sensors 90working in conjunction with a touch pad 92. The leads connecting theelectrodes of four separate closed-loop sensors 90 to the electrodes ofa single touch pad 92 are illustrated. As shown by closed-loop sensors90, if absolute position information is not necessary, and only relativemotion is needed, the electrodes of the closed-loop sensor can be laidout as repeating patterns of subsets of three or more sensor electrodes.When the same subsets are repeated multiple times in each closed-loopsensor, the sensor signals cannot be used to determine which of thesubsets is interacting with the input object. However, the position ofthe input object can be determined within the subset and, if the subsetis large enough such that the input object will not move beyond thesubset before the next data sample is taken, relative position of theinput object can be determined between consecutive positions andcompared to calculate motion of the input object.

Repeated subsets of electrodes are especially useful if the closed-loopsensor is large, since each electrode in the repeated pattern can remainsmall to retain adequate resolution without increasing the complexity ofsensor circuitry significantly. Repeated subsets are also useful if fineresolution is needed as many more sensor electrodes can be put in asmall distance to increase the resolution without increasing thecomplexity of sensor circuitry. Repeated electrodes are also useful ifit is desirable to control many relative position closed-loop sensorswith a single integrated circuit, because it reduces the number ofdistinct sensor inputs (or input lines) that need to be supported in thecircuit. Additional methods can be used to further decrease the numberof distinct sensor inputs, such as multiplexing the sensing circuitryacross multiple sensor electrodes.

FIG. 31 illustrates another way that one Cartesian touch pad can be usedto control a plurality of closed-loop sensors. Each of the closed-loopsensors can be linked to the same set of sensor inputs that isassociated with the first axis of the Cartesian touch pad. Thus, thecorresponding electrodes on each closed-loop sensor will be linked tothe same sensor input. Each of the closed-loop sensors can also belinked to distinct ones of the electrodes of the second axis of theCartesian touch pad. This can be accomplished by running a separate“indicator” sense electrode along the loop path of each closed-loopsensor and linking these indicator electrodes to distinct sensor inputson the second axis. The indicator electrode can be located anywhere nearthe closed loop, and of any shape, as long as it will indicate userinput when the user interacts with the relevant closed loop.

With indicator electrodes linked to the sensor inputs of the second axisof the Cartesian touch pad, if the signals from the sensor inputs of thesecond axis are similar to that expected when the Cartesian touch pad isbeing used, then the host device can determine that the Cartesian touchpad is being used. For example, an input object on a typical capacitivetouch pad causes the capacitance registered by the sensor inputs tochange in a characteristic manner; the sensor inputs associated with theelectrodes closest to the input object indicate the greatest change incapacitance; the sensor inputs associated with electrodes further fromthe input object indicate smaller changes in capacitance; the sensorinputs associated with electrodes furthest from the input objectindicate the smallest changes.

Thus, the configuration above in which indicator electrodes are linkedto the second axis can indicate when a closed-loop sensor is being used.For example, a user placing an input object on a closed-loop sensor withan indicator electrode coupled to a touch pad will cause the sensorinput associated with the indicator electrode to indicate a large changein capacitance. However, the input object will not cause the sensorinputs associated with adjacent electrodes of the second axis to vary inthe characteristic pattern described above that is associated with aninput object on the touch pad. Thus, the host device can determine thata closed-loop sensor is being used and act accordingly. In oneembodiment, the indicator electrodes are laid out and shielded such thatminimal capacitive coupling occurs between the input object and theindicator electrodes of the closed-loop sensors not being touched by theinput object; with this embodiment, significant signal on the sensorinputs of the second axis comes from only the sensor input associatedwith the indicator electrode of the closed-loop sensor being touched,and negligible signal comes on the other sensor inputs of the secondaxis. Signals from the first axis would indicate position and motion onthe closed-loop sensor, while signals from the second axis wouldindicate which closed-loop sensor is being used.

FIG. 31 illustrates two closed-loop sensors 90 electrically connectedwith a touch pad 92. When an input object touches the touch pad 92, theinput is read by the sensor inputs as changes in adjacent ones of secondaxis sensor inputs (demarked by x's and represented by numeral 103 inFIG. 32). In contrast, when an input object touches the closed-loopsensor 90, the input is read as changes (demarked by o's and representedby numeral 101 in FIG. 32) in the sensor input associated with indicatorelectrode 100 (represented by sensor input 1 in FIG. 32). This enablesthe processor (not shown) to determine which device is being utilizedfor the present fumction. Although two closed-loop sensors 90 areillustrated, several other closed-loop sensors may also be connected tothe touch pad 92 and can also have indicator electrodes. These indicatorelectrodes may be connected at any one of the positions illustrated byarrows 102.

In another embodiment, control electronics designed for a Cartesiantouch pad can be used in the manner of FIG. 31, but without an actualtouch pad sensor, as a simple cost-effective way to implement acollection of closed-loop sensors.

In the case that multiple closed-loop sensors are being operated atonce, or closed-loop sensors and the touch pad are being operatedsimultaneously, the characteristic signal shape (such as spikes of largechanges in capacitance on some sensor inputs and not others) can be usedto indicate which closed-loop sensors are being used and the signals canbe decomposed appropriately. In cases where the host device cannotdetermine which sensors are being used, then another indication of whichsensors are used can be indicated through key presses, button clicks,gestures on the touch pad, or other input. This would enable the hostdevice to extract useful information about which sensor is being touchedfrom the superimposed signals, or the system can use this information toreject simultaneous input on multiple sensors.

In addition to using indicator loop electrodes, multiplexing inputs andoutputs in time can also be used to determine which of a plurality ofclosed-loop sensors have caused an input. Other methods of multiplexingover time or over separate sensor inputs and driving circuitry are alsoviable.

The present invention can have an inactive region in the center of theloop path that comprises a protrusion, a depression, or a surface in thesame plane as the sensor. Alternatively, the closed-loop sensor can alsohave a physical button, or multiple buttons, in the center. Theclosed-loop sensor can have a hole for a physical button in the centeror the center can be one or more touch sensitive zones (or activationzones), which can also be used to emulate one or more buttons. Theclosed-loop sensor can have a pointing stick, track ball, small touchpad, or other input device in the center. The closed-loop sensor canhave one or more physical buttons beneath it that are activated bypressing on the closed-loop sensor.

FIG. 33 illustrates a top view of an exemplary closed-loop sensor 110having a pointing stick 112 disposed in the center of a bezel of theclosed-loop sensor 110. For the purposes of this disclosure, numeral 112represents an exemplary pointing stick. One skilled in the art wouldrecognize that the pointing stick 112 could be any shape, design orconfiguration. FIG. 34 illustrates a side view of the cross-section ofthe closed-loop sensor 110. The pointing stick 112 is disposed in thecenter of the closed-loop sensor 110 surrounded by an interior portion114 of the bezel. The loop path 116 is defined by interior portion 114and also by an exterior portion 115 of the bezel. In one application ofthe arrangement in FIG. 33, pointing stick 112 can serve as the pointingdevice for a laptop computer, and the closed-loop sensor 110 can serveas the scrolling device.

FIG. 35 illustrates the lightning-bolt design sensor 120 having aninterior opening 122 for the installation of, for example, a pointingstick, and four exterior regions 124 that can be touch sensitive zones(or activation zones) that emulate buttons. If desired, the touchsensitive zones can also be used to estimate pressure of contact if theinput object is similar to a finger in its tendency to spread out andcover a greater area of the sensor with increased contact pressure. Thisadditional information can be used to increase the functionality of thesensor. The closed-loop sensor can detect taps, presses, and othergestures, which can be used to control general-purpose input/output(GPIO) pins or reported in a data packet.

Multiple closed-loop sensors can be implemented as a set of nestedclosed-loop sensors defined on a single position detector, or onmultiple position detectors, with each closed-loop sensor controlling adifferent feature of the user interface. Determining the angular θposition of the input object in such a set of nested closed-loop sensorsis the same as in determining the angular θ position of the input objectin a single closed-loop sensor. These nested closed-loop sensors can actas independent input devices. They can also be used together as parts ofone control—such as in a vernier-type control in which outer loops areassociated with coarser control and inner loops are associated withfiner adjustment. Nested closed-loop sensors can also be used togetherto generate a one-and-a-half dimensional or a two-dimensional inputdevice. For example, a set of nested closed-loop sensor can be formedfrom a concentric set of circular closed-loop sensors having varyingradii. In the one-and-a-half dimensional version, the position detectormonitors which closed-loop sensor has the strongest input signal to makea gross estimate of the input object position.

In the two-dimensional version, signals from the set of nestedclosed-loop sensors are interpolated to more accurately generate aradial r position of the input object. Algorithms similar to those usedto calculate linear coordinates can be used for calculating the radial rcoordinates. Depending on the design of the radial sensor electrodes,scaling or weighting of individual electrode signals-may be necessary toaccommodate for the larger or more numerous sensor electrodes in theloops farther away from the center of the nested sensors. However, aftersuch scaling (if necessary), conventional methods for interpolation toestimate position and for estimating motion can be used. Since theradial r position is known to a finer resolution than the number ofconcentric closed-loop sensors in the set of nested sensors, the rinformation can be used to enable the set of nested sensors to emulatemore closed-loop sensors than the actual number of closed-loop sensorsphysically in the nested set. The preceding applications of buttons,keys, pointing sticks, touch screens, touch sensitive zones, and thelike, with a single closed-loop sensor can also be applied to a positiondetector having multiple closed-loop sensors.

FIG. 36 illustrates an object position detector 130 having fourclosed-loop sensors to vary the settings of audio controls. Althoughfour separate closed-loop sensors are shown, any number of closed-loopsensors can be utilized. Using the volume control closed-loop sensor 132as an example, the motions (illustrated by arrow 134) of an input objecton the volume control closed-loop sensor 132 will cause the volume ofthe audio system to either increase or decrease. Likewise, otherclosed-loop sensors on object position detector 130 can be used forbalance and the levels of treble and bass for an audio system.

The multiple closed-loop system can be applied in alternative ways. FIG.37 illustrates another object position detector 140 for an audio systemhaving two sets of nested sensors (142 and 144) consisting of concentriccircles of two closed-loop sensors. Each of the two sets of nestedsensors (142 and 144) has separate closed-loop sensors to controlseparate functions for the audio system. For example, nested set ofsensors 142 has a first closed-loop sensor 146 for bass and a secondclosed-loop sensor 148 for treble. Other nested closed-loop sensorshapes are contemplated in addition to concentric circles.

Another alternative multiple closed-loop system is an object positiondetector 150 for an audio system having four closed-loop sensorsdisposed in concentric circles (or other appropriate shapes) asillustrated in FIG. 38. The four separate closed-loop sensors eachcontrol a separate function in the audio system. For example,closed-loop sensor 152 controls volume, closed-loop sensor 154 controlsbalance, closed-loop sensor 156 controls treble, and closed-loop sensor158 controls bass.

Position algorithms can be used to calculate the position along a closedloop, which can be expressed as angular coordinates for roughly circularclosed-loop sensor designs, of an input object, including a quadraticfitting method, a centroid interpolation method, a trigonometricweighting method, and a quasi-trigonometric weighting method. When theclosed-loop sensor is implemented as a capacitive sensor, thecapacitance measurements from the sensor electrodes are preferablycombined using an interpolation algorithm for greater precision.

A preferred interpolation method is quadratic fitting, as illustrated inFIG. 39. This method typically involves three steps. In the first “peakdetection” step, the electrode with largest capacitance measurement isdetermined to be electrode number i, where the N electrodes are numberedfrom 0 to N−1. The number i is an initial, coarse estimate of the inputobject position. The capacitance measurements are normally made againsta non-zero background capacitance on each electrode. This background (noinput object) capacitance arises from a number of factors such as chippin capacitance and circuit board ground plane capacitance. Many ofthese effects vary from sensor to sensor and vary over time, so it ispreferable to use a dynamic calibration algorithm to subtract out thebaseline. First, the capacitances C′(j) of all the electrodes 0≦j≦N aremeasured at a time when no input object is present; and stored in atable C₀(j). Then, when an input object is present, the electrode inputobject capacitance measurement, C(j), is preferably computed from thecapacitances of all of the electrodes C′(j) as C(j)=C′(j)-C₀(j).

In the second “quadratic fitting” step, the three capacitancemeasurements from the three adjacent electrodes numbered i−1, i, and i+1are fitted to an inverted parabola, as is illustrated in the graph inFIG. 40. The three (x, y) coordinate points (i−1,C(i−1)), (i,C(i)), and(i+1,C(i+1)) define a unique parabola or quadratic function bywell-known mathematical principles. In a closed-loop sensor, theelectrode numbering is taken modulo N so that electrodes 0 and N−1 areadjacent. Once the parameters of the parabola fitting the threeelectrodes are determined, the true mathematical center point X(indicated by arrow 172) of this parabola is calculated. This will be afractional number near the value i. The number X can be reduced modulo Nif necessary.

In the third, optional, “adjustment” step, the value X is passed througha non-linear function designed to compensate for any non-linearities dueto non-idealities in the electrode design. It is realized that no sensorpattern will produce a completely ideal result for any particularinterpolation algorithm. Therefore, the computed position will have some“wobble” as the input object moves around the length of the sensor.

However, because the sensor electrode pattern is rotationally symmetric,this wobble will repeat in equivalence to the spaces between theelectrodes. The wobble will depend on where the input object is betweentwo electrodes, and not on which electrode the input object is disposed.Mathematically, if the true input object position is X_(f) and theinterpolated position is X, then X=w(X_(f)) for some “wobble” functionw(x). Because w(x) is periodic, the position can be written in terms ofits integer and fractional parts as X_(f)=int(X_(f))+frac(X_(f)), andthe wobble can be expressed as X=int(X_(f))+w(frac(X_(f))). The natureof w(x) can be determined theoretically or by experimental measurements;its inverse c(x) can then easily be computed or approximated usingwell-known techniques in the art. Because c is the inverse of w, thefinal computed position is X′=c(X)=c(w(X_(f)))=X_(f), so that X′ iscompensated to reproduce the true input object position X_(f). Becausew(x) is a periodic function, its inverse c(x) will also be periodic.Thus, the final computed position is calculated asX′=int(X)+c(frac(X)=int(X_(f))+c(w(frac(X_(f)))=int(X_(f))+frac(X_(f))=X_(f).This analysis assumes 0≦w(x)<1, which is not necessarily true; asomewhat more elaborate analysis shows that the technique works for anyinvertible periodic function w(x). It will be obvious to those skilledin the art that an analogous adjustment step can be used with anyinterpolation method on circular sensors.

The resulting position X′, falling in the range 0≦X′<N, represents theangular position of the input object in units of electrodes. The numberX′ can be multiplied by 360/N to convert it into an angular position indegrees.

An alternate interpolation method, often used in the art, is centroidinterpolation, as illustrated in FIG. 41. This method computes themathematical centroid of the curve of capacitance measurements and isadapted to closed-loop sensors by locating the peak electrode number i,and then rotating the coordinate system by renumbering each electrode jto (j−i+N/2) modulo N. This moves peak electrode i to the approximatecenter of the sensor for purposes of the centroid calculation. After thecentroid calculation produces a position X, the reverse rotation isapplied, X′=(X+i−N/2) modulo N, to produce the final angular inputobject position.

A second way to adapt the centroid method is to use trigonometricweights, as illustrated in FIG. 42. In this method, a numerator N iscomputed as N=sum(sin(i*2*pi/N)*C(i)) and a denominator D is computed asD=sum(cos(i*2*pi/N)*C(i)), where C(i) is the capacitance measurements ofthe N electrodes and i ranges from 0 to N−1 in the sums. The arctangentatan(N/D) then yields the desired input object position. Preferably, afour-quadrant arctangent, commonly written atan2(N,D), is used to obtainan angular position over the full circle. The sine and cosine weightfactors are constants that can be pre-computed and tabulated. Becausethe sums N and D are linear in C(i), it is possible to distribute outthe baseline subtraction C(i)=C′(i)-C₀(i) to become a simple subtractionof baseline sums N₀ and D₀. It may be preferable to use thetrigonometric method when memory resources are too limited to store afull set of baseline capacitance values.

A useful generalization of the above method is to use aquasi-trigonometric weighting method, as illustrated in FIG. 43. Insubstitution of standard sine, cosine, and arctangent trigonometricfunctions, other periodic functions f_(S), and f_(C), such as trianglewaves, and corresponding inverse function f_(A)f_(S), f_(C)), can beused. In the case of triangle waves, some loss of resolution is tradedfor greater linearity and simpler math calculations. The primary causeof this loss in resolution is due to the discontinuities in the trianglewave that generates discontinuities in the interpolation.

A loop path that inherently closes on itself poses an interestingchallenge in determining motion from the positional data from thesensor. If data is sampled at discrete times, then the change inposition at two different times can have occurred via two differentdirections. The method for determining motion for a closed-loop sensoris described as follows and is illustrated in FIG. 44.

After each sampling period, the input object position NewPos iscalculated and it is determined whether an input object (e.g., finger,stylus, pen, implement, or other input object) is or is not present onthe sensor. If the input object was not on the sensor during theprevious sample, NewPos is copied into OldPos. If an input object ispresent, the following method is completed. Because the sensor is aclosed loop, there are two paths an input object can take between anytwo points on the sensor. For example, if the first position (OldPos) isat 0 degrees and the second position (NewPos) is at 90 degrees, then theinput object can have traveled 90 degrees from 0, 1, 2, . . . , 88, 89,to 90 or the input object can have traveled 270 degrees from 0, 359,358, . . . , 92, 91, to 90. To resolve this, the assumption is made thatthe input object cannot travel more than 180 degrees around the sensorbetween two consecutive samples. To calculate motion, OldPos issubtracted from NewPos to determine the amount of motion between the twosamples (Motion=NewPos-OldPos). If the resulting Motion is 180 degreesor more, the assumption is that the input object must have traveled theother direction, so 360 degrees is subtracted from Motion. Likewise, ifthe resulting Motion is less than −180 degrees, the assumption is thatthe input object must have traveled in the opposite direction, so 360degrees is added to Motion. The “signed” modulo 360 of the result isthus taken such that the ultimate result of this motion calculation fromone sample to the next, is constrained to, for example, −180≦Motion<180degrees around the sensor. The sign of Motion gives the direction oftravel and the absolute value of Motion gives the magnitude or distanceof travel. In all cases, the algorithm completes by copying NewPos ontoOldPos.

This algorithm of determining motion, in which the input object isassumed to travel an angle of −180≦Motion<180 degrees between twoconsecutive samples, can be generalized to accommodate differentsampling rates and shapes or sizes of the loop. For alternate shapes orsizes of closed-loop sensors, appropriate assumptions of maximum angle,minimum angle, or maximum distance of travel can be made based on theclosed-loop path layout and the sampling period. In the case of verylong sampling periods or very small loop paths, when the maximum angle,minimum angle, or distance of travel is no longer sufficient fordetermining the path of travel of the object between two samples, thenan assumption can be made about the more likely path (such as that theshorter path is more likely) or additional information can be used (suchas using history of motion in the form of three or more samples toestimate the direction of travel).

The motion information output of this closed-loop sensor can beimplemented in many ways and contain various amounts of information,including absolute positions or relative positions (i.e., motions). Themotion output can also be used to emulate a physical wheel encoder andoutput two-bit gray code (sometimes called “quadrature states”), inwhich case the closed-loop sensor can be added to any existing devicewhich accepts two-bit gray code with no modification to the originaldevice's electronics.

When using a closed-loop sensor implemented on a two-dimensional touchsensor having both radial and circular sensor electrodes but without aphysical constraint (or tactile guide) defining the closed-loop path, itis possible that the input object will gradually move out of the definedloop path. This may result in a variable scaling of the distancetraveled to angular velocity, depending on the location of the motionwith respect to the center of the motion, which may result in acalculated magnitude of input significantly different from that intendedby the user. For example, small motions near the center of the definedloop path map to larger angular velocities than the same small motionsnear the periphery of the loop path. Users are typically more able tocontrol the absolute distance traveled of the input object than theangle traveled by the input object relative to a defined center. Thus,for an input, in which the distance from the center is not useful, suchas scrolling along a page or controlling the volume, users typicallyexpect the output to be mapped to the distance traveled rather than tothe angle, and may prefer small motions anywhere in the loop path togenerate similar outputs.

Therefore, in the case where the user's input object is not physicallyconstrained to a particular closed-loop path, some adjustment isdesirable in the angular speed due to the user wandering closer andfarther from the center point. If no adjustment were completed,positions closer to the center point would cause more angular change fora given amount of motion, which is not desirable from a human-factorspoint of view. Several adjustments are possible, including simplyscaling the angular speed by 1/R, as well as more complicated and errorprone scaling mechanisms, such as varying the center point to compensatefor the estimated user deviation from the center of the loop path.Scaling the angular speed by 1/R involves dividing the angular speed byR (the radius from the center) of the system such that small motionsnear the center will not result in large outputs.

Another method is to use the angular component solely to determine thesign of the traversal along the closed-loop path, and calculate thespeed based only on the absolute motion of the object, as illustrated inFIG. 45. For example, given two consecutive points sampled from theclosed-loop sensor, the straight-line distance is calculated betweenthese two points (with an approximation to the Pythagorean Theorem orequivalent polar coordinate equations). Additionally, the angularpositions corresponding to these two points along the closed-loop pathare calculated by one of the means previously discussed. The angle ofthe second point is subtracted from the angle of the first point, andthe sign of this result is used to indicate the direction of motion,while the absolute distance is used to indicate the amount of motion.This results in a more natural feeling correspondence between the motionof the user's input object and the corresponding variation in thecontrolled parameter (e.g., scrolling distance, menu traversal, orsetting value).

In the case that the closed-loop sensor is not circular or substantiallycircular, the algorithms used to calculate position for a circularsensor could still be used to estimate an input object's position. Inthis case, the algorithm will indicate where the input object(s) is(are)in the closed loop of the closed-loop sensor, and software can decodethe exact location based on knowledge of the local electrode design. Forexample, a closed-loop sensor having a rectangular loop with roundedcorners can have software that can differentiate the signals generatedby an object very near, or on, the corners versus the signals generatedby an object along a linear portion of the rectangle. The previouslydiscussed algorithms can generate this information and compensate.

The present disclosure discloses several advantages. A touch sensor isdisclosed having a closed-loop sensor, or a designated loop path alongwhich a user can move an input object, where the action ofscrolling/selecting/varying is controlled by the motion of the inputobject along the loop path. For example, the direction, the distance oftravel, or the speed of the input object can provide the control input.The closed-loop sensor also has the additional advantage of not beinglimited by mechanical design or human anatomy in enabling a user tomaneuver through a document, through menus, or along a range of valuesfor a control. For example, a user can easily-move an input objectaround a closed-loop sensor in a continuous manner, and draw a pluralityof loops within the sensor area, with the number of loops drawn limitedonly by the fatigue of the user or the functional life of the sensor.

The present invention has many uses, including for scrolling, movingthrough a menu, A/V uses (fast forward, rewind, zoom, pan, volume,balance, etc.), two-dimensional/three dimensional data presentation,selection, drag-and-drop, cursor control, and the like. Manyapplications have application-specific elements that can benefit fromthe type of control achieved by using the closed-loop sensor of thepresent invention. For example, a game can benefit from having acontinuously variable control that can be used as a steering wheel, adial, or other control that indicates direction and magnitude of motion.Another example is for use with a CAD program that allows the user torotate/translate/scale the viewpoint of a model or to vary the color ofan element smoothly. A further example is a text editor, which canbenefit from a smooth and continuously varying input to control the zoomlevel of its text. In general, any application parameter or control thatneeds to vary over a large range of possible values can benefit from thepresent invention. Physical processes (e.g., to control the position ofa platform, the speed of a motor, the temperature or lighting in acompartment, and the like) can also benefit from the use of closed-loopsensors.

The closed-loop sensor of the present disclosure frees users fromtargeting tasks or from remembering complex combinations of controls byallowing designers of applications or operating systems to reduce scrollbars and other similar display controls to mere indicators of thecurrent scrolled position or control value. If scroll bars and similardisplay controls can be reduced to mere indicators, their size can bereduced and their positions at the edge of the screen, edge of a window,or other specific location on the screen or window will consumenegligible space. Additionally, the freedom offered by reducing scrollbars and similar display controls might allow menus to be lesshierarchical, which further reduces control and display complexity.

The manufacturing cost and complexity of a host system can be reduced byusing a single solid state sensor with multiple closed loops to replacemany of the various controls currently present on such systems. Themanufacturing cost and complexity of incorporating closed-loop sensorsinto a host system can also be reduced by integrating the closed-loopsensor with existing object position sensors (e.g. touch pads and touchscreens) and taking advantage of existing sensor inputs to theelectronics of the existing position sensor. Portions of ageneral-purpose position sensor, such as the sensor regions, theelectronics, and the firmware or driver of the general-purpose positionsensor, can be reused with closed-loop sensors, which can providefurther savings in space and money.

Additionally, the solid-state nature of capacitive and inductiveclosed-loop sensors makes them more reliable and durable. Such sensorscan be sealed and used in environments where knobs and other physicalcontrols are impractical. The present invention can also be made smallerthan knobs or other physical controls, and requires very little spaceand can be custom made to almost any size. Additionally, the operationof the sensor has low power requirements, making it ideal for portablenotebook computers, personal digital assistants (PDAs), and personalentertainment devices.

The closed-loop sensor can also be used to provide additionalinformation that a knob or scroll bar would not, such as the size of thecontact between the object on the sensor and the sensor itself.Additionally, some closed-loop sensors may be able to distinguishbetween a finger and a pen, or indicate some other quality ororientation of the input object. This information can further be used toincrease the functionality of the controller through “gestures” on theclosed-loop sensor. For example, the speed or range of scrolling ordisplay adjustment can be adjusted as a function of the speed of theinput object's motion or the distance traveled by the input object.Additional gestures, such as tapping, executing predefined motionpatterns, having a stationary input object and a moving input objectsimultaneously, or moving two input objects in two directions along theloop of the sensor, can indicate different actions to the host device.The starting point of contact of the input object to the host deviceprogram for the input can also be used. For example, a motion startingfrom a first region of the sensor and progressing in a first directioncan indicate panning of the display, while motion starting from the samefirst region and progressing in a second direction can indicate zoomingof the display. Meanwhile, a motion starting from a second region canindicate a desire to scroll horizontally, and the direction of motioncan indicate the direction of scroll. This can be extrapolated toadditional regions that map to additional functions.

While the invention has been described with reference to an exemplaryembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the presentinvention. In addition, many modifications may be made to adapt aparticular situation or material to the teachings without departing fromthe essential scope thereof. Therefore, it is intended that theinvention not be limited to the particular embodiments disclosed as thebest mode contemplated for carrying out the present invention, but thatthe present invention will include all embodiments falling within thescope of the claims.

What is claimed is:
 1. An object position detector, comprising: a touchscreen, said touch screen including a touch sensor and an electronicdisplay, said electronic display configured to indicate a closed looppath on the electronic display, said touch sensor overlaying at least apart of said display and configured to sense object motion proximatesaid touch sensor; and a processor coupled to said touch screen, saidprocessor configured to generate a signal for causing scrollingresponsive to sensed object motion along said closed loop path indicatedon the electronic display.
 2. The object position detector of claim 1,wherein said electronic display comprises an LCD.
 3. The object positiondetector of claim 2, wherein said closed loop path is indicated on saidtouch screen using LCD projections.
 4. The object position detector ofclaim 1, wherein said touch sensor comprises a capacitive touch sensor.5. The object position detector of claim 1, wherein said touch sensorcomprises a resistive touch sensor.
 6. The object position detector ofclaim 1, wherein said closed loop path is substantially circular.
 7. Theobject position detector of claim 1, wherein said closed loop pathincludes a starting position along said closed loop path, and whereinsaid processor is further configured to cause an action different fromscrolling responsive to sensed object motion starting proximate saidstarting position and proceeding along said closed loop path.
 8. Theobject position detector of claim 1, wherein said electronic display isfurther configured to indicate at least one touch sensitive zoneproximate said closed loop path, said touch sensitive zone configured toemulate a button.
 9. The object position detector of claim 1, whereinsaid signal is representative of one of a position and a motion of saidobject.
 10. The object position detector of claim 1, wherein saiddisplay is further configured to indicate a second closed loop path, andwherein said processor is further configured to generate a signal forindicating a user interface navigation task responsive to sensed objectmotion along said second closed loop path.
 11. The object positiondetector of claim 10, wherein said closed loop path and said secondclosed loop path are not nested.
 12. A solid-state object positiondetector for indicating a desired user interface navigation task,comprising: a touch screen, said touch screen including a touch sensorand an electronic display, said electronic display configured toindicate a substantially closed loop path on said touch sensor, saidtouch sensor overlaying at least a part of said electronic display, saidtouch sensor configured to sense motion of an object proximate saidtouch sensor; and a processor coupled to said touch screen, saidprocessor configured to provide relative motion information responsiveto sensed motion of said object along said substantially closed looppath, said relative motion information representative of a differencebetween a first position and second position of said object, saidrelative motion information indicating said desired user interfacenavigation task.
 13. The solid-state object position detector of claim12, wherein said electronic display comprises an LCD.
 14. Thesolid-state object position detector of claim 12, wherein said touchsensor comprises one of a capacitive touch sensor and a resistive touchsensor.
 15. The solid-state object position detector of claim 12,wherein said desired user interface navigation task comprises scrolling.16. The solid-state object position detector of claim 12, wherein saidprocessor is further configured to provide absolute position informationabout said object.
 17. The solid-state object position detector of claim12, wherein said desired user interface navigation task comprisesadjusting a value.
 18. The solid-state object position detector of claim12, wherein said display is configured to indicate a secondsubstantially closed loop path on said touch sensor, and wherein saidprocessor is further configured to provide relative motion informationfor causing a second desired user interface navigation task responsiveto sensed motion of said object along said substantially closed looppath.
 19. An object position detector, said object position detectorcomprising: a touch screen, said touch screen including a touch sensorand an electronic display, said electronic display configured toindicate a substantially closed loop path surrounding an interiorregion, said interior region not part of said closed loop path, saidtouch sensor configured to sense object motion proximate said touchsensor; and a processor coupled to said touch screen, said processoradapted to generate a signal for causing scrolling in a first directionresponsive to clockwise sensed object motion along said substantiallyclosed loop path, said processor further adapted to generate a signalfor causing scrolling in a second direction responsive tocounter-clockwise sensed object motion along said substantially closedloop path.
 20. The object position detector of claim 19, wherein saidclosed loop path is indicated on said touch screen using projections.21. The object position detector of claim 19, wherein said touch sensorcomprises one of a capacitive touch sensor and a resistive touch sensor.22. The object position detector of claim 19, wherein said processor isfurther adapted to generate a second signal for emulating a buttonresponsive to sensed object motion in said interior region.
 23. Aprogram product comprising: a) a touch screen program, said touch screenprogram adapted to indicate a closed loop path on a touch screen, saidtouch screen program further adapted to generate a signal for causingscrolling responsive to sensed object motion along said closed loop pathon said touch screen; and b) computer-readable media bearing said touchscreen program.
 24. The program product of claim 23, wherein said touchscreen program is further adapted to: process signals to determineobject motion on said touch screen; indicate a second closed loop pathon said touch screen; generate a different signal for a user interfacenavigation task responsive to sensed object motion along said secondclosed loop path on said touch screen.
 25. The program product of claim24, wherein said touch screen program adapted to indicate a secondclosed loop path on said touch screen is adapted to: indicate saidsecond closed loop path on said touch screen not nested with said firstclosed loop path.